An infrastructure for supplying a hydrogen-containing gas used as a fuel at the time of power generation is not developed as a typical material infrastructure, so that a fuel cell system typically includes a hydrogen generator including a reformer configured to generate a hydrogen-containing gas from a natural gas or LPG supplied from the typical material infrastructure.
In the reformer, a steam-reforming reaction is typically used. In the steam-reforming reaction, for example, a city gas and steam that are materials are caused to react with each other at a high temperature of about 600 to 700° C. by using a precious metal-based reforming catalyst, such as a Ni-based reforming catalyst or a Ru-based reforming catalyst. Thus, the hydrogen-containing gas containing hydrogen as a major component is generated.
A material gas, such as the city gas, contains a sulfur compound. Since the sulfur compound is a poisoning material especially for the reforming catalyst, it has to be removed in some way. As one removing method, there is a hydrogen generator configured to remove the sulfur compound by hydrodesulfurization using a recycled hydrogen-containing gas.
Here, a hydrogen generator has been proposed, which stabilizes the supply of a recycled gas in such a manner that a hydrogen-containing gas is stored for a predetermined period of time in a gas-filled portion of a gas-filled container disposed on a recycled gas passage used for recycling, and then the hydrogen-containing gas is mixed with a material (for example, PTL 1).